I suppose it depends on which part of the country you're interested in....or will you have time to visit from the Caribbean to the Pacific? It's a little country with many eco-zones which lend themselves to difference types of fruit growing. For instance the avocado and mango farms are in the more dry Pacific side, but there are a number of small individual growers of many fruit varieties there. The Caribe side is wetter, and there are many large farms growing pineapples, bananas, rambutan and many other tropicals that like the humidity. On my side (the Caribbean) we have CATIE and EARTH which are well-known agricultural research universities which grow scores of different fruits. CATIE has many many acres of large mature tropical fruit trees to see, and there are knowledgeable people at the botanical gardens to show you around. A great choice for a "working farm" is Finca la Isla in Puerto Viejo on the East Coast. You probably know Peter Kring from this discussion board. He an expert and has been commercially growing scores of tropicals for 30 years. Check out some others on youtube.com.